Ford has announced fuel-economy figures for the 2013 Fusion Energi plug-in hybrid, which goes on sale in January, and the sedan’s EPA ratings vault it to the top of the plug-in-hybrid sedan fuel-efficiency heap. Granted, that heap is pretty short—it currently includes just the Toyota Prius plug-in, the Chevrolet Volt, the Fisker Karma, and Ford’s own C-Max Energi—but the Fusion Energi’s 100-MPGe (miles-per-gallon of gas equivalent) combined rating nonetheless grants Ford efficiency bragging rights for the time being.

Ford’s Energi sedan’s other economy figures are 108 MPGe in the city and 92 on the highway, and all three numbers mirror those of the C-Max Energi. There, as they say, lies the rub, of course—Ford is being dragged into the spotlight over the veracity of the impressive fuel-economy claims for its C-Max hybrid (the non-plug-in C-Max variant) and Fusion hybrid. That’s not to say the Fusion Energi’s numbers are false or misleading, but it shares its powertrain with the cordless Fusion hybrid and the C-Max twins, so Ford’s claims for its hybrids could all soon fall under question. For reference, Toyota’s Prius plug-in is rated for 95 MPGe combined; the Chevy Volt is good for 98 (its numbers were increased for 2013); and the Fisker Karma musters just 54.

Against the segment’s most-visible player, the Chevrolet Volt, the Fusion Energi brings more than just a higher MPGe figure—it’s slightly less expensive, to boot. The Ford starts at $39,495, $500 less than the Volt; the Chevy wins in electric-only range, however, with a 38-mile rating for electric-only running to the Fusion Energi’s roughly-20-mile gas-free operating radius.